Improvement in processes for preparing wood for mechanical reduction to paper-pulp



UNITED S'r'rEs PATENT OFFICE.

GEORGE E. MARSHALL, OF TURNERS FALLS, MASSACHUSETTS.

IMPROVEMENT IN PROCESSES FOR PREPARING WOOD FOR MECHANICAL REDUCTION T0 PAPER-PUL P.

Specification forming part of Letters Patent No. 193,261, dated July 17, 1877 application filed June 30, 1877. v

' poplar, and other woods preparatory to their being used in the manufacture of woodpulp for making paper-stock.

It is well known that poplar, spruce, and

other Woods used in the manufacture of pulp for paper-stock should all be cut in the winter season, while the grain of the wood is comparatively free from sap, and before it begins to ascend in the spring. This involves the necessity of keeping a large supply of the wood on hand for several months, or during the whole of the remainder of the year, as it is unfit for use when full of sap or frozen.

In keeping the wood for use several months, it, of course, becomes seasoned, and comparatively dry and hard, the gum, resin, acetic, and pinic acids become hard and fixed in the grain of the wood, and more or less insoluble. To removethese substances, and to render the wood fresh and soft for the best working condition, many processes have been attempted, but none with entire success. The wood has been boiled with alkalies and Without. It has also been subjected to great pressure with steam, and other treatments, somewhat varied from these, have been tried; but in all these processes the wood is discolored-in some more than others-pausing an additional expense to bleach it, and some of them are very expensive in the consumption of fuel and of chemicals.

I purpose, by my invention, to accomplish the desired object at areasonable expense, and without the difliculties encountered in packed. At the bottom of this tank is an 7 opening, through which the water, of a temperature under the boiling-point, is forced, by a hydraulic press, to such an extent as completely to saturate and thoroughly to permeate the wood, and to soften and drive out of the pores the gum, the resin, and the acids. This may be somewhat aided by the introduction of a small quantity of some alkaline substance to partially acton the acids, but not sufficient to color the wood.

To aid in this operation, and to allow the superfluous and deleterious matter thus disengaged from the wood to pass away, an opening is made in the top of the tank, provided with a valve, gaged to allow the water, at any regulated high pressure, to pass 011', thus constantly washing away the impurities rendered soluble and free by the introduction of the heated slightly alkaline water. The wood is continued in this condition until it is cleansed, freshened, and softened fit for the grindingmachines.

What I claim, in preparing wood for the mechanical manufacture of pulp for paper-stock, 18-- The process of removing the gum, acids, and other deleterious matter preparatory to grinding, by subjecting the wood to a high degree of pressure of water under the boiling-point, all substantially as described.

Witness my hand this 25th day of June, A. D. 1877.

. GEO. E. MARSHALL.

Witnesses:

W. H. P. GILMORE, W. D. RUSSELL. 

